A typical sample separation system for separating components of a sample fluid (particularly a sample liquid) comprises an injector for injecting the sample fluid into a mobile phase, and a fluid drive system for driving the mobile phase and the sample fluid through a separation unit, preferably a chromatographic column, which is adapted for separating components of the sample fluid in the mobile phase.
In high performance liquid chromatography (HPLC) the mobile phase is pressurized up to 1000 bar and above. In particular due to the high pressures it may occur that sample fluid leaks between an injection needle and a seat. Moreover, a carry-over of samples between subsequent injections may occur.
U.S. Pat. No. 6,526,812 B2 relates to a self-washing injection apparatus. The self-washing injection apparatus for liquid chromatography injection valves utilizes an interior chamber with a penetrable seal at a top end of the chamber and a needle sleeve seal at a bottom end of the interior chamber. A wash port in the body of the apparatus connects one or more sources of wash fluid to the interior chamber between the penetrable seal and a sleeve seal. The apparatus provides means to aspirate or pump wash fluids from one or more wash fluid reservoirs through the apparatus, the injection port of the injection valve and associated components. In particular, once the needle has been withdrawn from the apparatus, the injection port apparatus and the injection port of the injection valve may be washed or flushed utilizing the wash port.